The presence of low numbers of tumor cells (micrometastases) in hematopoietic tissues in patients with a variety of solid-tumor malignancies is of extreme clinical relevance. In breast prostate, and lung cancer patients, the presence of micrometastases is significantly associated with poor prognosis and early relapse. However, tumor cells exist in very low numbers, making sensitive detection difficult. In Phase I studies we developed a monoclonal antibody-based tumor enrichment column (TEC) system that enriches tumor cells from marrow and blood nearly three logs, to one tumor cell in 108 hematopoietic cells. In patient specimens, the TEC system resulted in superior detection of micrometastatic tumor cells. In Phase II studies, we propose to expand clinical testing of the TEC system to patients with breast, prostate, and lung cancers. This will allow us to determine the clinical and diagnostic utility of the system in a variety of malignancies where micrometastases are of clinical concern. The TEC diagnostic kit will allow laboratory and clinical scientists to more sensitively and accurately detect, stage, and monitor patients, occult metastatic tumor burden. PROPOSED COMMERCIAL APPLICATION: These studies will result in a commercially available kit for tumor cell enrichment of breast, prostate, and lung cancer micrometastases. This kit will allow laboratory and clinical scientists/pathologists to more sensitively and accurately detect and monitor patients' occult tumor burden. This has the potential to greatly advance cancer diagnostics for solid-tumor malignancies.